Influence Of150℃-400℃High Temperature Dry Curing Regime On Mechanical Properties Of Reactive Power Concrete (RPC)

In this paper, an experimental investigation was conducted to study the mechanical properties of the hybrid fiber reactive powder concretes (RPC) after150℃-400℃high temperature heating curing regime.After heating at different temperatures (150℃,200℃,250℃,300℃,350℃,400℃), the mechanical properties of hybrid fiber RPC under different curing conditions including2different water-binder ratios (0.14,0.16),2%volume dosage of steel fibers and0.15%PP fibers were all investigated. The influence of temperature (150℃,200℃,250℃,300℃,350℃,400℃) and heating time (4h,6h and8h) was studied on the mechanical properties development of reactive powder concretes after heating curing, in order to find a curing system to improve the mechanical properties of RPC.The curing process of this paper is:after hed in the mold for24hours, then put all the specimens into90℃water for2days. Finally, the specimens were heated to attended temperature (150℃,200℃,250℃,300℃,350℃,400℃) maintaining for different durations (4h,6h and8h).The results of these tests reveal that the surface features of reactive powder concretes which heated at different curing regime conditions are different. Compared with the color of RPC cured at standard curing system, the color of which heated after150℃,200℃and250℃, is slightly different; and with time extended, the surface features of specimens change little. After heated at400℃, the color of RPC specimens become slight brown; and with the time extended, the surface color gradually darken.Strength test results reveal that after the heating curing regime, with the temperature increasing, the compressive strength and splitting tensile strength of reactive powder concretes with different water-binder ratios all increased at first, then decreased, and the peak achieved at250℃. After heated at different maintaining durations(4h,6h and8h), the strengths of reactive powder concretes with different water-binder ratios (0.14and0.16) heated after6h are higher than heated after4hours and8hours. Therefore, among the different heated times of heated system,6-hour is the best heated time.Fracture energy test results reveal that after the heating curing regime, with the curing temperature increasing, the fracture energy of reactive powder concretes with different water-binder ratios all increased at first, then decreased, and the peak achieve at300℃. After heated at different maintaining durations(4h,6h and8h), the fracture energy of reactive powder concretes with different water-binder ratios (0.14and0.16) heated after6h are higher than heated after4hours and8hours. Therefore, among the different maintaining duration of dry curing regime,6-hour is the best curing time.The above results reveal that after heated at250℃for6hours, the compressive strength and splitting tensile strength of RPC reach the highest. When heated at300℃for6hours, the fracture energy of reactive powder concretes reach the highest.